defended by israel's new hero, the iron dome, an antimissile missile system made in israel helped with american money. of 900 rockets fired at israel in six days, only about 30 hit populated areas. >> we enjoy the iron dome, which is a huge success. and luckily -- >> reporter: there's a siren now. let's see what happens. it will only fire. the system calculates which rockets will hit an inhabited areas, like here, but it misses 2 out of 10, making life scary. children in bomb shelters for the sixth straight day. i'm afraid of the sirens, this 7-year-old says. another siren -- just as we left, not sure how many rockets have been fired right now, but the iron dome -- one, two, three, four iron dome rockets are exploding. we'll see what damage it did. five rockets fired from gaza, four intercepted, one got through and fell in a garden. there's some drama right now. nobody knows if there's casualties. terrifying some neighbors. others defiant. >> we will survive. we will survive. >> nbc's martin fletcher reporting. israel's iron dome comes with a hefty price tag. the u.s. has reportedly sp